The first sighting of the animal that makes the tracks was made by a visiting researcher in May, and it seems to be a Water Rat, Hydromys chrysogaster, due to its size (large), colour (dark brown with a white tip to the tail) and hairiness (very, including on the tail).

This is the first record of a native terrestrial mammal on the island. Non-native Black Rats have made their way to Lizard Island on a few occasions but populations have never become established.